The present invention relates to the measurements performed in systems for radiocommunication with mobiles.
Such measurements are usable in particular in procedures for controlling the radio links which serve in a general manner to optimize the quality of the transmissions and to minimize the interference between users. Among these procedures mention may be made of the regulating of transmission power by the mobiles and/or by the infrastructure, the control of automatic cell transfers (handovers) in cellular networks, the adaptation of the channel coding to the propagation conditions, the adaptation of the source coding (in particular the case of variable rate speech encoders of AMR “Adaptive Multi-Rate” type), the link adaptation procedures, etc.
The Efficiency of this kind of procedure depends on the availability of reliable energy measurements within as short a time span as possible, so that suitable decisions can be taken fairly quickly.
On the other hand, certain situations do not require any account to be taken of overly frequent energy measurements. In particular, when the conditions are favourable on the radio channel considered, occasional measurements may suffice in order to implement the radio links control procedures, without encumbering the signalling channels transmitting the reports of measurements performed to a control facility and without excessively invoking the processing resources of the control facility for analyses of measurements that will lead, with a small probability only, to useful changes in the management of the radio resources.
This twofold requirement has been taken into account in certain systems such as UMTS (“Universal Mobile Telecommunication System”) with the possibility of defining two modes of uploading measurements from a fixed or mobile transceiver to a radio network controller, on the latter's initiative:                a periodic mode, in which reports of measurements are transmitted regularly to the network controller, with an upload period specified by the controller, between 250 ms and 64 s; and        an event-based (“event-triggered”) mode of reporting, where the occurrence of a specified event, detected by the terminal or by the fixed transceiver, causes the despatching of a report message to the controller.        
This distinction, as well as the details of the events that may give rise to a transition between each of the two modes are described in greater detail in 3G TS 25.331 technical specifications, version 4.1.0, “RRC Protocol Specification”, and 3G TS 25.433, version 41.1.0, “UTRAN Iub Interface NBAP Signalling”, published in June 2001 by the 3GPP.
At present, only a limited set of events making it possible to switch over from the periodic mode to the event-based reporting mode and vice versa is envisaged. Such events are generally based on an analysis of the field level of a radio signal received. By way of example, the event designated 1F envisages the triggering of uploads of measurements, to the network controller, over a radio link, when the field level of a signal received over this link goes beyond a threshold level.
As things currently stand, the events specified for switching over from one mode of uploading measurements to the other do not comprise technical indicators for taking account of more precise criteria, this possibly leading to the maintaining of too high or too low a measurement reporting tempo in certain cases. However, a poor choice of the rate of measurement reports may have consequences possibly as extreme as a break-off in communication, for example when measurements of field level over neighbouring cells are not uploaded by a mobile terminal to the radio network controller frequently enough to allow a transfer of the communication from the serving cell to these neighbouring cells, although the quality of the communication was rapidly degrading over the current link.
An object of the present invention is to propose a finer way of achieving a compromise between uploads of measurements to a radio network controller that are frequent enough to allow better control of the radio resources, on the basis of up-to-date measurements, and a limitation of these same uploads of measurements so as to avoid an overload of signalling on the radio pathway and a monopolizing, by these measurements, of the radio network controller's processing means.